Photographic materials useful for forming dye images according to a method which includes a bleaching step are known and commercially used. Such materials and methods are described, for example, in The Theory of the Photoqraphic Process, Fourth Edition, edited by T. H. James, pages 462 to 463 and pages 335 to 361. The use of a bleach accelerator releasing coupler in such photographic material is described in Research Disclosure, No. 11449 (1973) and Japanese Patent Application (OPI) No. 201247/86 (the term "OPI" as used herein means a "published unexamined Japanese patent application").
However, it has been found that while bleach accelerators released from these bleach accelerator releasing couplers exhibit a certain degree of effect in the case of using a fresh developing solution, their bleach accelerating effect remarkably decreases under a conventional running condition wherein a developing solution or other solution has been carried over into a bleaching solution or a bleach-fixing solution.
Such a phenomenon may be explained as follows.
A bleach accelerator which is released from a bleach accelerator releasing coupler in a developing solution adsorbed to developed silver. In this case, an active species may be a thiol compound or a disulfide compound, although it is difficult to specify which compound is the active species. However, since it is known that a thiol forms a disulfide by aerial oxidation, etc., particularly rapidly in an alkaline solution as described in Shin-Jikkenkaqaku Koza, Vol. 14, page 1735, Maruzen (1978), a disulfide is presumably formed during development processing.
It is known that the thiol or disulfide formed which is a bleach accelerator is attached by sulfite ion present in a developing solution and produces a thiol sulfonate as described in L. C. Schoroeter, Sulfur Dioxide, page 145, Pergamon Press (1966). Accordingly, it is believed that a reason for the decrease in bleach accelerating effect under the running condition described above is that a thiol or disulfide forms a thio sulfonate ion with a sulfite ion carried over from a developing solution to a bleaching solution and loses adsorptive power to developed silver.
Thus, these known bleach accelerator releasing couplers are insufficient in bleach accelerating effect under practical running conditions and further improvement has been desired.
Further, couplers which have a thioether group at the coupling position are described, for example, in U.S. Pat. Nos. 3,227,554 and 4,293,691. These couplers are useful as so-called DIR couplers or two-equivalent couplers. However, they have an insufficient bleach accelerating effect and some of them rather deteriorate bleaching property.